USA TODAY reported uninsured children are also discharged from the hospital earlier and are less likely to get expensive treatments.
"The clear implication ... is that when kids get sick or hurt, insurance matters," Ron Pollack, executive director of Families USA, which conducted the study, told USA TODAY. "As is true throughout our health care system, children without health insurance receive less and inferior care."
Hospital organizations challenged the study's findings, saying it didn't take important factors into account, including the type of hospitals studied and the details of each child's condition.
"I consider the study irresponsible because it is not sufficiently thorough," Chip Kahn, president of the Federation of American Hospitals, told USA Today.
The report was sent to congressional committees looking at proposals to help insure the nation's 9 million uninsured children, the newspaper reported.